Stitch-forming mechanism for chain-stitch sewing machines



. A. F. FIFIELD. STITCH FORMING MECHANISM FOR CHAIN STITCH SEWING MACHINES.

APPLICATION FILED SEPT. @1920! 1 ,421,438 Patented J My 4, 1922 2 SHEETS-SHEET 1.

INVENTOR M4 ff/fmw ATTORNEY A. F. FIFIELD.

STITCH FORMING MECHANISM FOR CHAIN STITCH SEWING MACHINES. APPLICATION FILED SEPT. 2, I920.

1,42 1,43 Patented July 4, 1922 2 SHEETSSHEET 2.

" im I 6 WITNESSES:

.JNVENTOR ALBERT 1F. FIFIELD, OF NEWARK, NEW JERSEY, ASSIGNOR TO THE SINGER IJIANfi- FACTURING COMPANY, OF ELIZABETH, NEVI JERSEY, A CORPORATION OF NEW JERSEY.

a; Specification of Letters Patent.

Patented July 4, 19229 Application filed September 2, 1920. Serial No. 407,622.

To all whom it may concern:

Be it known that l, ALBERT F. FIFIELD, a citizen of the United States residing at Newark, in the county of Essex and State of New Jersey, have invented certain new and useful Improvements in Stitch-Forming Mechanisms for Chain-Stitch Sewing Machines, of which the following is a specification, reference being had therein to the accompanying drawings.

This invention relates to single chainstit-ch sewing machines of the wellknown rotary looper type disclosed, for example, in the United States patent to Willcox No. MAW) of September 27, 1864:.

In machines of this type, as commonly constructed. it is essential to the formation of enchained loops that the work'be fed in the direction in which the looper-beak moves when in loop-seizing position, in order that the descending needle may pass in front of both limbs of the previously formed loop held spread by the looper, whereby the looper-beak may first seize the nascent needleloop and subsequently pass between the limbs of the previous needleloop. These machines, therefore, while well adapted for straightaway sewing in the direction in which the looper-beak moves in seizing a needle-loop. are practically inoperative when an attempt is made to sew while feeding the work in a direction opposite to the direction of movement of the looper-beak in seizing a needle-loop. the reason being that there is no provision for insuring that the needle will descend in front of both limbs of the previously formed needle-loop and that the previous needle-loop will be held spread in a position such that the beak of the looper will pass into it as is essential to the stitchforming operation.

In utilizing chain-stitch mechanism of the rotary looper type in connection with a jogging work-holder such as is used in button sewing or attaching price marks for example. in which; in forming some ofthe stitches. a component of movement is given to the work in a direction opposite to the direction in which the looper-beak moves in seizing the' needle-loop, itwas found that by vibrating the looper-shaft laterally and making use of a loop-detaining spur or finger into engagement with which the limbs of the previous needle-loop were carried by bodily jogging movements of the looper the said spur or finger being disposed at the opposite side of the needle-path from the loop-spreading portion of the looper-beale It has been found that under high speed operation the looper of the chain stitch mechanism of said patent under certain conditions fails to enchain the needle-loops and it is evidently caused by a limb of the loop, due to the high speed, whipping around the end of the loop-detaining spur or finger so that it is positioned to the front thereof and the limbs of the loop are therefore not held on the rear side of the needle-path as is neccssary for a proper enchaining of the needleloops. As the outer limb of the loop is shed around the outer edge of the heel portion of the looper-beak, it being stressed as it passes over this edge and then suddenly becoming slack, the slack is sufficient to allow this limb to be carried around the end of the detaining spur or finger because of its momentum under high speed.

An object of the present invention is, therefore. to improve the well known single chain-stitch mechanism of the rotary looper type so that it will cnchain the needle-loops properly and with certainty when the work isgi'ven a component of movement in a di rection opposite to the direction of movement of the looper-beak in its loop-seizing stage of movement.

Another object of the invention is to provide a sewing machine having stitch-forming mechanism of the rotary looper type adapted to form detached groups of fastening stitches in the formation of which relative jogging movements between the stitch- :i'orming mechanism and work are employed and some of these movements are in a direction opposite to the direction of movement of the beak of the looper when entering the loop to seize the same.

Still further the invention has for an ob ject to prevent a limb of the needle-loop passing around the end of the loop-detalning spur or finger to the front thereof, so that it will be properly positioned by this spur or finger for entrance of the looper.

Further objects of the invention will appear from the following description and claims.

To attain these ends I have provided a looper of the rotary type with means for temporarily detaining the limb of the needleloop after it has been shed or passed over the outer edge of the heel of the beak portion of the looper, until the slack has been taken up sufficiently by the loop-deflecting and spreading wing of the looper to prevent the limb passing or flipping over the free end of the loop-detaining spur or linger to the front thereof.

In the preferred construction this means comprises a pin set into the outer curved portion of the loop-deflecting: and spreading wing of the looper at about the junction of this wing with the heel of the beak portion of the looper inwardly of the outer edge of this heehand projecting a short distance from the surface of the looper at substantially right angles thereto. Referring to the accompanying drawings; Fig. 1 is a front elevation of the free end of the machine bed or work-arm with a portion thereof broken away to disclose the looper, the work-h.older being shown in elevation. F 2 is a bottom plan View of the free end of the work-arm. Fig. 3 is a sectional elevation through the worlearm in a plane at about the free end of the looper showing the needle-loop in the position it occupies just before its outer limb is snapped over the edge of the heel of the looper-heak. Figs. l and 5 are end and side elevations, respectively, of the looper showing its relation to the needle and work, the loopcr being in the position occupied immediately after the outer limb of the thread-loop snaps over the heel of the looper-beak. Figs. 6 and T are Views similar to Figs. i and 5 but showing the position of the thread-loop after the slack therein has been taken up by the loopspreading and twisting portion of the looper, and Fig. 8 is a view similar to Figs. 4t and 6 showing the beak of the looper as about to pass a ncedle-loop through a previously formed loop.

In the particular embodiment of the invention illust'ated the machine frame com prises a work-supporting arm 1 above which is the head 2 in which is journaled the reciprocating needle-bar 3 carrying the eyepointed needle 4:.

The present machine is provided with a work-clamp and operating mechanism thereforconstructed substantially in accordance with the disclosure of my Patent No. 1,226,- of May 22 191.7. and is adapted to bandle either two or 'l'our-hole buttons. The work-clamp comprises the jogging bar 5 which extends longitudinally of and rests upon the work-arm 1. To the forward end of the bar 5 is secured the fabric supporting plate 6 upon which rests the button-clamp comprising the opposed button-gripping jaws 7', 7 carried by the spring-pressed arm 8 secured upon a block (not shown) mounted ipon the rearward end of the bar 5. Mechanism is provided for imparting longitudinal and transverse jogging movements to the work-clamp as clearly disclosed in my said Patent No. 1,226,963 and as this mechanism forms a part of the prior art and is not wlaimed specificially herein, further illustration and description thereof is believed to be unnecessary. It maybe stated, however, that when the present machine is adjusted to sew four-hole buttons the Work-holder is given movements having a component ofmovement in a direction opposite to the direction of movement ofthe looper-beak in its loopseizing movement. 7

Jonrnaled within and lengthwise of the work-arm 1 is a rotary looper-shaft into the enlarged and soclieted end 9 of which is secured the shank of the rotary looper formed with a loo-p-.seizing beak 10- and with the loopdeflecting spreading, and twisting wing ll. hip; portion of the looper and the wing 11 is a throat 13., the bottom of which affords a groove havingi; forward and rearward ere trcinities serving to spread the forward and rearward limbs a', b, respectively, of the needle-loop seized by the looper. Set into the looper on the opposite side from the throat l3 and at substantially the junction of the heel 12 of the beak-forming portion and the wing ll. is a pin i l for a purpose presently to be desirribed. This pin is rigid with the looper and extends outwardly a short distance from its surface at substantially right angles thereto. As shown in Figs. 5 and 7 it is located inwardly a short distance from the outer edge of the heel 12.

The end "of the looper-shaft adjacent the looper is journaled in a block 15 slidably mounted in guideways 16 in the under side of the worlearm so that during the operation of the stitch-forming mechanism the looper-shaft may be vibrated laterally.

Rigidly secured to the under side of the throat-plate 17 is a loop-detaining spur or finger 18 formed with a recess 19 on its rear side as shown in Fig. 2, in which at certain times the limbs of the needle-loop are detained after they are carried into engagement therewith by the bodily jogging movements of the looper and work-holder. 'The said spur or fingeris disposed at the opposite side of the needle-path from the loopspreading portion of the looper-beak in its loop-seizing stage of movement as shown in Between. the heel 12 of the bealr-foi'm- Fig 8 and serves to position the limbs of the i'ieedle-thread loops uniformly regardless of the position of the last stitch. This mechanism more fully disclosed. in m Patent No. 1,147;3860f July 20, 1915i It has been found, however,-that when this mechanism is operated at high speed the looper sometimes fails to properly enchain the thread-loops or in other words the machine skips stitches. As the needle-loop is seized and expanded by the beak 10 of the looper it is kept taut until the outer limb a is snapped over the outer edge of the heel 12 of the beak-forming portion of the looper when. because of the peculiar shape of the looper. it immediately becomes slack, as shown in Figs. a and 5, and this slack is sufficient to allow the limb a of the loop to pass around the end of the detaining spur or finger 18 to the front thereof or to the same side of this spur as is the needle-path, as shown in dotted lines a in 'Fig. 4:. Under high speed operation this sometimes happens when the limbs of the loop lead from a point in the work to the front of the detaining spur. or finger 18 or on thesame side as the needle-path when the work as button B and fabric F is jogged to the right, as shown in Fig. 1, because .the sudden change from being taut to being slack as the limb (1. passes over the edge of the heel 12, together with its momentum carry it around the end of the spur or finger '18. It

will therefore be apparent that when this condition exists both limbs of the'needleloop are not held on the opposite side of the ncedlepath from the looper-beak in. its loop-seizing stage of movement and therefore it cannot carry the nascent loop through the previously formed loop and the loops are not enchained.

However. when the pin or detaining means 141 is employed, as the limb a of the needleloop is snapped around the edge of the heel 12 it is detained by said member 14 and heldas shown in Figs. at to 7, until as the looper rotates the loop-spreading and twist ing wing 11 has taken up suflicient slack to prevent the 'limb a from passing around the end of the spur or finger 18 as shown in Figs. (3 and 7. At this time the rotation of the looper carries the member 14: out of the path of the limb or releasing the same so that the loop may be properly twisted and positioned by the wing 11 and throat 13 for entrance of the next loop.

Although in my preferred construction the member 14 is a pin set into the looper so as to be rigid therewith as shown it obviously does not necessarily have to be of such construction, as the same operation and effect may be obtained by other structures, for example. by means of a lugformed integral with the looper.

It has been found that this simple expedient effectively prevents the mechanism as disclosed from skipping stitches under high speed.

Member 20 is an oscillating and bodily movable needle-guard. It, however, forms no part of my present'invention and therefore it is not further described herein. Its function and operation. is fully disclosed in my said Patent No. 1,147,386, above mentioned.

Mounted so that its free end bears lightly upon the surface of the looper is a flat spring or finger 21 forming aloop-controller to prevent a previously formed needle-loop flipping around over the beak of the looper and thus causing. a breaking ofv the loop. This device may or may not be employed with my present device. It is fully disclosed in my Patent No. 1,316,022 of September 16, 1919. I

At the end of the stitching operation the thread-cutter 22 mounted on bellcrank-lever 23 pivoted'to thethroat-plate at 24 is oper ated to cut the thread by the stop-mechanism.(not shown) through th'e draw-bar 25. This mechanism, however,- forms no part of the present invention. and. is substantially the structure disclosed .inmy: Patent No. 1251,451 dated December 25, 1917.

In the various figures the arrows indicate the directions in which the parts are moving. Having thus set forth the nature of the invention, what I claim herein is 1. In a sewing machine, in combination, a reciprocating needle, a rotary looperhaving a loop-seizing beak and a loop-spreading wing,'means adapted to position the loop at one side-of the. needle-path, and means on the looper to; temporarily detain a limb of the loop after it hasbeen passed aroundthe outer end of the looper.

2. In a sewing machine,'in combination, a reciprocating needle, a rotary looper having a loop-seizing beak and a loop-spreading wing. means for detaining the loop at one side of the needle-path, and means on the looper adapted to temporarily. detain a limb of the loop after-ithas been passedover the outer end of the looper until the slack in the loop has been taken up by the action of the loop-spreading wing of the looper.

3. In a sewing machine, incombination,

a reciprocating needle, a rotarylooper having a loop-seizing beak and a loop-spreading wing, at loop-detaining spur or finger adapted to detain the loop at one side of the needle-path, and means to temporarily detain a limb of the loop after it has been passed around the outer end of the looper until the slack in the loop has been taken up sufficiently to prevent its flipping around the end of the loop-detaining spur or finger.

1. In a sewing machine, in combination, a reciprocating needle, a rotary looper having a loop-seizing beak and a loop-spreading wing, a loop-detaining spur or finger having a free end and adapted to detain the loop at one side of the needle path, and means to detain a limb of the loop after it has passed over the outer edge of the heel of thelooper beak until the loop-spreading 6, In a sewing machine, in combination with a reciprocating needle, a rotary looper havin a loop seizing beak and a loopspreading ti ing, feeding means adapted to impart to the Worka component of movement ina direction oppositeto the direction of theloop-seiz ing movement of the looperbealnmeans to "detain the loop at one side o fth e needle-path, and means on the looper for temporarily detaining limb of the loop after it has been shed around the outer edge e heel of the looper beak.

. In asewing machine, in combination,

:a reciprocating needle, a rotary looper having a loop-seizingbeak and aloop-spreading and" twisting portion, :a- V thread-detaining finger adapted to position the thread-loop zit one side of the needle-path, and means on the looper adaptedto detain one limb of the needldoop after it has snapped over the heel of the looper-beak until the loopspreading and twisting portion of the looper has acted upon the opposite limb of the loop to take" up the slack therein.

8. In a sewing machine, in combination, a reciprocatingneedle, a rotary looper having aloop sei'zingbeak and a loop-spreading and twisting" portion, a loop-detaining spur or fingei' adapted to position the threadloop atone side of the needlespath, and means on the looper adapted to detain alimb oi the needle-loop in rear of the loop detainihgspur or fingeruntil the loopspreading and twisting portion of the looper hasacted o'nthe opposite limb of the loop to take upsufiicient slack to prevent the first limb passing around the end of the loop-detaining spur or finger to the front thereof.

jection extending outwardly from the surface of the looper at the back of the loop spreading Wing and at substantially the junction of this ing With the beak portion of the looper. r

10. In a sewing machine, in combination,

a reciprocating needle, a rotary looper having a loop-seizing beak and a loop-spreading Wing, means for positioning the loop at one side ofthe needle-path, and means in addition to said beak and wing for temporarily detaining a limb of the loop after it has been passed over the outer end of the looper.

11.- In a sewing machine, in combination with a reciprocating needle, a rotary looper having a loop-seizing beak and a loopspreading Wing, means for causing a relative movement between the Work and the looper having a component in a direction opposite to the direction of the loop-seizing movement of the looper-beak, means to tie tain the loop at one side of the needle-path, and means for temporarily detaining a limb of the loop after it has been shed around the outer edge of the heel of the looper-beak.

12. In a sewing machine, in combination, a reciprocating needle, a rotary looper hav ing a loop-seizing beak and a low-spreading wing, means for positioning the loop at one side of the needle-path and means cooperating Withthe wing of the looper for controlling the slack in the loop after it has passed around the outer end o'f the looper.

In testimony whereof, I have signed my name to this specification.

ALBERT F. FIFIELD. 

